#include <iostream>
#include <cstring>
#include <algorithm>

using namespace std;

bool cmp(vector<int> &A, vector<int> &B)
{
    if(A.size() != B.size()) return A.size() > B.size();
    for(int i = A.size()-1; i>=0; i--)
        if(A[i] != B[i]) 
            return A[i] > B[i];
            
    return true;
}

vector<int> sub(vector<int> &A, vector<int> &B)
{
    vector<int> C;
    for(int i = 0, t = 0; i < A.size(); i++)
    {
        t = A[i] - t;
        if(i < B.size()) t -= B[i];
        C.push_back((t+10)%10);
        if(t < 0) t = 1;
        else t = 0;
    }
    while (C.size() > 1 && C.back() == 0) C.pop_back();
    return C;
}

int main()
{
    string a, b;
    vector<int> A, B;
    cin >> a >> b;
    for (int i = a.size()-1; i >= 0; i -- ) A.push_back(a[i]-'0');
    for (int i = b.size()-1; i >= 0; i -- ) B.push_back(b[i]-'0');
    vector<int> C;
    if(cmp(A, B)) C = sub(A, B);
    else C = sub(B, A), cout<< '-';
    for (int i = C.size()-1; i >= 0; i--) cout << C[i];
    cout << endl;
    return 0;
}